Generally speaking, a common electronic device has a display interface and a control interface set at the front side, while connecting/transmission wires or a heat dissipation module are set at the back side of the electronic device. Some of the electronic devices, such as a set-top box (STB), which includes a removable interface structure at the back side of the electronic device for adapting to variety of transmission interface cards. Accordingly, an assembling opening is set at the back side of the electronic devices for user assembling or disassembling purpose. While the assembling step is completed, a cover plate is necessary to be screwed onto the back side for covering the assembling opening for preventing dust in the air from entering the electronic devices.
Please referring to FIG. 1, wherein a perspective view of a prior electronic device is shown. As shown in FIG. 1, an electronic device PA100 comprises a casing body PA1, a back casing PA2, and a back plate PA3. The back casing PA2 is fixed on the back side of the casing body PA1, and the back plate PA3 is removably set on the back casing PA2. The back casing PA2 has an assembling opening for assembling transmission interface cards into the electronic device PA100. The back plate PA3 is fastened and locked on the back casing PA2 by screwing after finishing assembling or disassembling the transmission interface cards.
In view of the above-mentioned, the user usually needs to remove the back plate for assembling or disassembling the transmission interface cards in practical applications. However, when the transmission interface cards are assembled or disassembled, the back plate may have already lost, so that the user needs to buy another back plate for covering the assembling opening of the electronic device. It causes inconvenience in assembling or disassembling the transmission interface cards, and increases a cost due to another back plate bought for covering the assembling opening.